There is a solid-state image-capturing device in which a pixel array unit having multiple pixels arranged in an array form in a two-dimensional manner includes not only ordinary pixels for image generation (hereinafter referred to as image-capturing pixels) but also phase difference pixels for focal point detection.
In order to obtain a high degree of phase difference detection accuracy with the phase difference pixels, the sensitivity needs to be highly dependent on the angle so that the phase difference pixels receive only the incidence light of a desired angle and generates an associated output.
In order to make the phase difference pixels of which sensitivities are highly dependent on the angle, it is most effective to increase the film thickness of an inter-layer film of a phase difference pixel (makes a thicker film).
However, when an inter-layer film is simply made thicker, the image-capturing pixels are also made into thicker films, and therefore, the image-capturing pixels would have a poor diagonal incidence property. More specifically, although it is desirable for the image-capturing pixel to receive light from a diagonal direction of which incidence angle is large, when the thickness of the film is increased, the light from diagonal direction may not be received and the sensitivity is reduced.
Therefore, a solid-state image-capturing device has been suggested to improve the detection accuracy of a phase difference pixel by employing a structure of the phase difference pixel which is different from the structure of the image-capturing pixel. For example, PTL 1 discloses a technique for making a structure of the phase difference pixel that is different from the structure of the image-capturing pixel by forming an in-layer lens in the phase difference pixel and embedding a high refraction index layer under the in-layer lens.
On the other hand, PTL 2 discloses an idea for changing the structure of the image-capturing pixel. More specifically an inter-layer lens and a light guide are provided for the image-capturing pixel, so that, while the degradation of the characteristics of the image-capturing pixel is suppressed, the phase difference pixel is optimized, whereby the detection accuracy of the phase difference pixel is improved.
In order to obtain a high degree of phase difference detection accuracy using a phase difference pixel, a light shielding layer for pupil-splitting serves an important role. Therefore, PTL 3 discloses a solid-state image-capturing device that helps a light shielding layer by making the aperture width of a wiring layer of the uppermost layer of the phase difference pixel smaller than the aperture width of the image-capturing pixel.